Lots of different ways to create slideshows with music for viewing from a DVD. I'm on Mac so I cannot make direct suggestions. Also, I use Final Cut Pro & DVD Studio Pro for the more complex projects so likewise maybe not comparable. However, Premier & FCP do have some kind of similarities. (And I've used Photoshop since it's simplistic days of version 1, but do not pretend to be any kind of expert.)
My thoughts are, go back to Premiere & do a Save As, add the extra images & possibly extra music. Then do the same kind of output/export as you did originally.

I've a hobby project that's been continuous for 5 years lol .. once a year or less bring it out & make a few changes. Originally objective was to convert a PAL VHS concert video to DVD since the concert of that artist has never been released onto DVD. I added slideshows & music from CD's & mp3's to make up the rest. Then decided to move to DVD-9 (7.6 GB actual workable size) & add more, plus some film clips, & do a % of music as PCM instead (the latter takes up a particularly large amount of space.) Project Save As, is used within DVD Studio Pro. But projects like mine get into the more complex options of multiple 'story' options, etc.

Not sure why your Organiser would save it all as WMV. I'm sure there is an option to disable that. WMV whilst a shareable format between computers, is not the most ideal for cross-platform sharing ( ie: Mac & Linux.)